X-Git-Url: https://git.saurik.com/apple/libc.git/blobdiff_plain/ad3c9f2af814c84582fdd1649e49ec4f68572c5a..e07eda1a0324f771bb1ed20ef94f3229005ee46c:/stdlib/FreeBSD/qsort.c diff --git a/stdlib/FreeBSD/qsort.c b/stdlib/FreeBSD/qsort.c index 1d0e3c5..b1c5257 100644 --- a/stdlib/FreeBSD/qsort.c +++ b/stdlib/FreeBSD/qsort.c @@ -10,7 +10,7 @@ * 2. Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in the * documentation and/or other materials provided with the distribution. - * 4. Neither the name of the University nor the names of its contributors + * 3. Neither the name of the University nor the names of its contributors * may be used to endorse or promote products derived from this software * without specific prior written permission. * @@ -31,8 +31,9 @@ static char sccsid[] = "@(#)qsort.c 8.1 (Berkeley) 6/4/93"; #endif /* LIBC_SCCS and not lint */ #include -__FBSDID("$FreeBSD: src/lib/libc/stdlib/qsort.c,v 1.15 2008/01/14 09:21:34 das Exp $"); +__FBSDID("$FreeBSD$"); +#include #include #include @@ -41,52 +42,54 @@ typedef int cmp_t(void *, const void *, const void *); #else typedef int cmp_t(const void *, const void *); #endif -#ifdef I_AM_QSORT_B -static inline char *med3(char *, char *, char *, cmp_t ^, void *) __attribute__((always_inline)); -#else -static inline char *med3(char *, char *, char *, cmp_t *, void *) __attribute__((always_inline)); -#endif -static inline void swapfunc(char *, char *, int, int) __attribute__((always_inline)); +static inline char *med3(char *, char *, char *, cmp_t *, void *); +static inline void swapfunc(char *, char *, size_t, int, int); -#define min(a, b) (a) < (b) ? a : b +#define MIN(a, b) ((a) < (b) ? a : b) /* * Qsort routine from Bentley & McIlroy's "Engineering a Sort Function". */ -#define swapcode(TYPE, parmi, parmj, n) { \ - long i = (n) / sizeof (TYPE); \ - TYPE *pi = (TYPE *) (parmi); \ - TYPE *pj = (TYPE *) (parmj); \ +#define swapcode(TYPE, parmi, parmj, n) { \ + size_t i = (n) / sizeof (TYPE); \ + TYPE *pi = (TYPE *) (parmi); \ + TYPE *pj = (TYPE *) (parmj); \ do { \ TYPE t = *pi; \ *pi++ = *pj; \ *pj++ = t; \ - } while (--i > 0); \ + } while (--i > 0); \ } -#define SWAPINIT(a, es) swaptype = ((char *)a - (char *)0) % sizeof(long) || \ - es % sizeof(long) ? 2 : es == sizeof(long)? 0 : 1; +#define SWAPINIT(TYPE, a, es) swaptype_ ## TYPE = \ + ((char *)a - (char *)0) % sizeof(TYPE) || \ + es % sizeof(TYPE) ? 2 : es == sizeof(TYPE) ? 0 : 1; static inline void -swapfunc(a, b, n, swaptype) - char *a, *b; - int n, swaptype; +swapfunc(char *a, char *b, size_t n, int swaptype_long, int swaptype_int) { - if(swaptype <= 1) + if (swaptype_long <= 1) swapcode(long, a, b, n) + else if (swaptype_int <= 1) + swapcode(int, a, b, n) else swapcode(char, a, b, n) } -#define swap(a, b) \ - if (swaptype == 0) { \ +#define swap(a, b) \ + if (swaptype_long == 0) { \ long t = *(long *)(a); \ *(long *)(a) = *(long *)(b); \ *(long *)(b) = t; \ + } else if (swaptype_int == 0) { \ + int t = *(int *)(a); \ + *(int *)(a) = *(int *)(b); \ + *(int *)(b) = t; \ } else \ - swapfunc(a, b, es, swaptype) + swapfunc(a, b, es, swaptype_long, swaptype_int) -#define vecswap(a, b, n) if ((n) > 0) swapfunc(a, b, n, swaptype) +#define vecswap(a, b, n) \ + if ((n) > 0) swapfunc(a, b, n, swaptype_long, swaptype_int) #ifdef I_AM_QSORT_R #define CMP(t, x, y) (cmp((t), (x), (y))) @@ -94,14 +97,11 @@ swapfunc(a, b, n, swaptype) #define CMP(t, x, y) (cmp((x), (y))) #endif +/* + * Find the median of 3 elements + */ static inline char * -med3(char *a, char *b, char *c, -#ifdef I_AM_QSORT_B -cmp_t ^cmp, -#else -cmp_t *cmp, -#endif -void *thunk +med3(char *a, char *b, char *c, cmp_t *cmp, void *thunk #ifndef I_AM_QSORT_R __unused #endif @@ -109,7 +109,7 @@ __unused { return CMP(thunk, a, b) < 0 ? (CMP(thunk, b, c) < 0 ? b : (CMP(thunk, a, c) < 0 ? c : a )) - :(CMP(thunk, b, c) > 0 ? b : (CMP(thunk, a, c) < 0 ? a : c )); + :(CMP(thunk, b, c) > 0 ? b : (CMP(thunk, a, c) < 0 ? a : c )); } #ifdef __LP64__ @@ -122,63 +122,97 @@ __unused int __heapsort_r(void *, size_t, size_t, void *, int (*)(void *, const void *, const void *)); #endif -static void -_qsort(void *a, size_t n, size_t es, +/* + * Simple insertion sort routine. + */ +static bool +_isort(void *a, size_t n, size_t es, void *thunk, cmp_t *cmp, int swap_limit, int swaptype_long, int swaptype_int) +{ + int swap_cnt = 0; + for (char *pm = (char *)a + es; pm < (char *)a + n * es; pm += es) { + for (char *pl = pm; pl > (char *)a && CMP(thunk, pl - es, pl) > 0; + pl -= es) { + swap(pl, pl - es); + if (swap_limit && ++swap_cnt > swap_limit) return false; + } + } + return true; +} + #ifdef I_AM_QSORT_R -void *thunk, -#else -#define thunk NULL -#endif -#ifdef I_AM_QSORT_B -cmp_t ^cmp, +static void +_qsort(void *a, size_t n, size_t es, void *thunk, cmp_t *cmp, int depth_limit) #else -cmp_t *cmp, +#define thunk NULL +static void +_qsort(void *a, size_t n, size_t es, cmp_t *cmp, int depth_limit) #endif -int depth_limit) { char *pa, *pb, *pc, *pd, *pl, *pm, *pn; - size_t d, r; + size_t d1, d2; int cmp_result; - int swaptype, swap_cnt; + int swaptype_long, swaptype_int, swap_cnt; loop: + SWAPINIT(long, a, es); + SWAPINIT(int, a, es); + swap_cnt = 0; + if (depth_limit-- <= 0) { -#ifdef I_AM_QSORT_B - heapsort_b(a, n, es, cmp); -#elif defined(I_AM_QSORT_R) + /* + * We've hit our recursion limit, switch to heapsort + */ +#ifdef I_AM_QSORT_R __heapsort_r(a, n, es, thunk, cmp); #else heapsort(a, n, es, cmp); #endif return; } - SWAPINIT(a, es); - swap_cnt = 0; - if (n < 7) { - for (pm = (char *)a + es; pm < (char *)a + n * es; pm += es) - for (pl = pm; - pl > (char *)a && CMP(thunk, pl - es, pl) > 0; - pl -= es) - swap(pl, pl - es); + + if (n <= 7) { + /* + * For sufficiently small inputs, we'll just insertion sort. + * + * Pass 0 as swap limit, since this must complete. + */ + _isort(a, n, es, thunk, cmp, 0, swaptype_long, swaptype_int); return; } + + /* + * Compute the pseudomedian. Small arrays use 3 samples, large ones use 9. + */ + pl = a; pm = (char *)a + (n / 2) * es; - if (n > 7) { - pl = a; - pn = (char *)a + (n - 1) * es; - if (n > 40) { - d = (n / 8) * es; - pl = med3(pl, pl + d, pl + 2 * d, cmp, thunk); - pm = med3(pm - d, pm, pm + d, cmp, thunk); - pn = med3(pn - 2 * d, pn - d, pn, cmp, thunk); - } - pm = med3(pl, pm, pn, cmp, thunk); + pn = (char *)a + (n - 1) * es; + if (n > 40) { + size_t d = (n / 8) * es; + + pl = med3(pl, pl + d, pl + 2 * d, cmp, thunk); + pm = med3(pm - d, pm, pm + d, cmp, thunk); + pn = med3(pn - 2 * d, pn - d, pn, cmp, thunk); } + pm = med3(pl, pm, pn, cmp, thunk); + + /* + * Pull the median to the front, starting us with: + * + * +-+-------------+ + * |=| ? | + * +-+-------------+ + * a pa,pb pc,pd + */ swap(a, pm); pa = pb = (char *)a + es; - pc = pd = (char *)a + (n - 1) * es; + for (;;) { + /* + * - Move b forward while it's less than the median + * - Move c backwards while it's greater than the median + * - When equal to the median, swap to the outside + */ while (pb <= pc && (cmp_result = CMP(thunk, pb, a)) <= 0) { if (cmp_result == 0) { swap_cnt = 1; @@ -203,45 +237,78 @@ loop: pc -= es; } + /* + * Now we've got: + * + * +---+-----+-----+---+ + * | = | < | > | = | + * +---+-----+-----+---+ + * a pa pc,pb pd pn + * + * So swap the '=' into the middle + */ + pn = (char *)a + n * es; - r = min(pa - (char *)a, pb - pa); - vecswap(a, pb - r, r); - r = min(pd - pc, pn - pd - es); - vecswap(pb, pn - r, r); + d1 = MIN(pa - (char *)a, pb - pa); + vecswap(a, pb - d1, d1); + d1 = MIN(pd - pc, pn - pd - es); + vecswap(pb, pn - d1, d1); + + /* + * +-----+---+---+-----+ + * | < | = | > | + * +-----+---+---+-----+ + * a pn + */ if (swap_cnt == 0) { /* Switch to insertion sort */ - r = 1 + n / 4; /* n >= 7, so r >= 2 */ - for (pm = (char *)a + es; pm < (char *)a + n * es; pm += es) - for (pl = pm; - pl > (char *)a && CMP(thunk, pl - es, pl) > 0; - pl -= es) { - swap(pl, pl - es); - if (++swap_cnt > r) goto nevermind; - } + int r = 1 + n / 4; /* n > 7, so r >= 2 */ + if (!_isort(a, n, es, thunk, cmp, r, swaptype_long, swaptype_int)) { + goto nevermind; + } return; } - nevermind: - if ((r = pb - pa) > es) + + d1 = pb - pa; + d2 = pd - pc; + if (d1 <= d2) { + /* Recurse on left partition, then iterate on right partition */ + if (d1 > es) { +#ifdef I_AM_QSORT_R + _qsort(a, d1 / es, es, thunk, cmp, depth_limit); +#else + _qsort(a, d1 / es, es, cmp, depth_limit); +#endif + } + if (d2 > es) { + /* Iterate rather than recurse to save stack space */ + /* qsort(pn - d2, d2 / es, es, cmp); */ + a = pn - d2; + n = d2 / es; + goto loop; + } + } else { + /* Recurse on right partition, then iterate on left partition */ + if (d2 > es) { #ifdef I_AM_QSORT_R - _qsort(a, r / es, es, thunk, cmp, depth_limit); + _qsort(pn - d2, d2 / es, es, thunk, cmp, depth_limit); #else - _qsort(a, r / es, es, cmp, depth_limit); + _qsort(pn - d2, d2 / es, es, cmp, depth_limit); #endif - if ((r = pd - pc) > es) { - /* Iterate rather than recurse to save stack space */ - a = pn - r; - n = r / es; - goto loop; + } + if (d1 > es) { + /* Iterate rather than recurse to save stack space */ + /* qsort(a, d1 / es, es, cmp); */ + n = d1 / es; + goto loop; + } } -/* qsort(pn - r, r / es, es, cmp);*/ } void #ifdef I_AM_QSORT_R qsort_r(void *a, size_t n, size_t es, void *thunk, cmp_t *cmp) -#elif defined(I_AM_QSORT_B) -qsort_b(void *a, size_t n, size_t es, cmp_t ^cmp) #else qsort(void *a, size_t n, size_t es, cmp_t *cmp) #endif